One of the sellers on Marktplaats.nl, a resident of Luxembourg identified by the handle Bundum, is offering 29 items, including one letter which he describes as “an original letter from Auschwitz dated Nov. 9, 1941 with censor’s seal.” Another letter, dated March 4, comes in an envelope with a stamp carrying the portrait of Adolf Hitler. Other listings by Bundum include ads for Nazi toy soldiers.

The seller attached low-resolution photos of the letters showing two 15-line pages with dense handwriting. The words are illegible from the photos.

The listings for the letters name no price, but a prisoner’s identity card from the Mathausen concentration camp is going for $512.

Marktplaats contains more than 2,100 Nazi-related objects, including swastikas and busts of Hitler, according to the website wo2.sharepoint.com.

In a legal statement, Marktplaats said it prohibits the sale of “offensive objects,” but users are responsible for abiding by the policy.

The chairman of the Dutch Auschwitz Committee, Jacques Grishaver, told NRC Handelsblad, the Dutch daily that reported last week about the sale, the sale was a sign of the mainstreaming of anti-Semitism. “This should not be socially accepted, and action against it should be undertaken,” he said.

The Dutch Center of Information and Documentation Israel, or CIDI, said it was looking into legal action against the website.